Borate Micro Emulsion and Method for Making the Same

ABSTRACT

The specification discloses a borate microemulsion product. In one embodiment, the borate microemulsion includes from about 24 to about 32 weight percent emulsified sodium pentaborate; and from about 24 to about 32 weight percent particulate boric acid suspended therein. The microemulsion has a density of about 9.5 to about 10.5 pounds per gallon at about room temperature. In certain embodiments, the microemulsion has a viscosity of about 1200 to about 1520 at a temperature of from about 66° F. to about 70° F. In certain other embodiments, microemulsion has a viscosity of about 1000 to about 3000 at a temperature of from about 70° F. to about 75° F.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of copending application Ser.No. 12/271,954, filed Nov. 17, 2008, which in turn is acontinuation-in-part of copending application Ser. No. 11/560,411, filedNov. 16, 2006. This application also claims the benefit of the earlierfiling date of copending provisional application 61/154,102, filed Feb.20, 2009.

FIELD

The present disclosure relates in general to water treatment technologyand, in particular, to an algaecide and buffer for use in residential,community, and commercial swimming pools as well as other man made waterenclosures. The present disclosure also relates to a borate-basedmicroemulsion product suitable for use in the treatment of swimmingpools and similar structures and to a method for making the borate-basedmicro emulsion product.

BACKGROUND

Conventionally, the growth of algae and other undesirable microorganismsin swimming pool waters has been suppressed by the use of halogen-basedchemical additives. In particular, liquid or solid forms ofchlorine-containing chemicals such as hypochlorous acid, hypochloritesalts, sodium dichloro-s-triazinetrione (dichlor), andtrichloro-s-triazinetrione (trichlor) have been added to swimming poolwaters as algaecides. While effective in reducing or preventing algaegrowth, these additives are lost relatively quickly due to evaporationand photo-degradation, i.e, light-induced decomposition. Moreover,chlorine-containing additives are typically corrosive to steel surfacesand may also be an irritant to the skin and eyes. Accordingly, it isdesirable to use alternative swimming pool treatment chemicals in orderto reduce or eliminate the need for treatment chemicals containingchlorine or other halogens as well as to mitigate some of the negativeattributes of chlorine and other halogen pool chemicals.

Attempts have been made to use boron-containing chemicals, such astetraborate salts (i.e., borax) and boric acid as alternative swimmingpool treatment chemicals. However, these chemicals are problematic. Theytend to form into solid blocks or lumps when contacted with water whichsink to the bottom of a pool due to the relatively limited solubility ofthe chemicals, or they tend to float on top of the water and areaesthetically displeasing. Crusts or scaling may also form on theinterior surfaces of the swimming pool as well. Further, boric acid isalso corrosive to metal fixtures and fittings.

In addition, the use of boric acid in swimming pools has been found topromote the formation of hypochlorous acid, which is an eye irritant, ifused in conjunction with chlorine-based treatment chemicals. Borax alsoexhibits problems with chlorine retention as it promotes thephoto-degradation of sodium dichloro-s-triazinetrione (i.e., dichlor)when the two chemicals are used together to treat pool water.

Thus, there remains a continuing need for improved alternative swimmingpool treatment chemicals.

SUMMARY

The above and other needs are met by a method for reducing the rate ofgrowth of algae in an enclosed volume of water, such as a swimming pool.The method includes the steps of providing a volume of water within aman made vessel and dissolving a treatment composition into the volumeof water in an amount sufficient to reduce the rate of growth of algaein the water. The treatment composition includes a chlorine-containingsanitizer and a buffer, for instance an algaecidal buffer, whichcomprises a borate salt. When dissolved in the water, the treatmentcomposition buffers the pH in a range from about 6.5 to about 8.8.

In one embodiment of the present disclosure, the algaecidal bufferpreferably includes a salt selected from the group consisting of saltsof octaborate, salts of pentaborate, salts of hexaborate and mixturesthereof. Suitable salts may include, for instance, sodium salts,potassium salts, lithium salts, magnesium salts, calcium salts, zincsalts, and mixtures thereof. Particularly preferred are sodium orpotassium salts including disodium octaborate salt, sodium pentaboratesalt, and sodium hexaborate. In certain embodiments, the treatmentcomposition consists essentially of the chlorine-containing sanitizerand the algaecidal buffer. In still further embodiments, the treatmentcomposition consists of only the chlorine-containing sanitizer and thealgaecidal buffer.

In certain embodiments, the amount of algaecidal buffer dissolved in thevolume of water is preferably from about 0.01 weight % to about 0.5weight %, of algaecidal buffer in pool water. However, in certain otherembodiments of the present disclosure, the amount of algaecidal bufferdissolved in the volume of water is preferably from about 0.001 weight %to about 0.1 weight %, of algaecidal buffer in pool water, and morepreferably from about 0.02 weight % to about 0.05 weight %.

Advantageously, as compared to prior art boron-containing additives, ithas been found that the salts of octaborate, pentaborate, and hexaborateused in the present dissolve more readily into the water and without theformation of crusts or scaling or floating debris or dust when contactedwith water. When added to the water in a solid form, the time until thealgaecidal buffer of the present disclosure is substantially dissolvedin the volume of water is preferably from about 0.1 to about 50 minutes.

After the algaecidal buffer is dissolved, the water generally has a pHof from about 6.5 to about 8.8. In certain embodiments, the waterpreferably has a pH of from about 6.5 to about 8.4, more preferably fromabout 7 to 8, and most preferably from about 7.2 to about 7.6. This pHrange is believed to be generally ideal for the operation andmaintenance of the pool.

In certain embodiments of the present disclosure, the method of thepresent disclosure preferably further includes dissolving an effectiveamount of a sanitizer into the volume of water, wherein the sanitizer isselected from the group consisting of chlorine-containing sanitizers,bromine-containing sanitizers, silver-containing sanitizers,zinc-containing sanitizers, copper-containing sanitizers, quaternaryammonium-compound containing sanitizers, ozone sanitizers, UVsanitizers, and mixtures thereof.

More preferably, the sanitizer includes chlorine-containing sanitizersselected from the group consisting of chlorine gas, hypochlorite salts,sodium dichloro-s-triazinetrione (dichlor), andtrichloro-s-triazinetrione (trichlor), and the amount of sanitizerdissolved in the volume of water is sufficient to provide from about 0.1to about 10 ppm of free chlorine (Cl^(−ve)) in the pool water. Theamount of sanitizer used is substantially reduced as compared to priorart usages of such sanitizers in the absence of salts of octaborate,pentaborate, and hexaborate added as an algaecidal buffer.

In general, the water, after the algaecidal buffer is dissolved therein,may remain substantially free of algae for at least about 7 days.

In another aspect, the present disclosure provides an algae-resistantwater vessel such as a swimming pool. The algae-resistant water vesselincludes a volume of water contained within a man-made vessel and atreatment composition dissolved in the volume of water in an amountsufficient to reduce the rate of growth of algae in the water, whereinthe treatment composition includes a chlorine-containing sanitizer and abuffer such as an algaecidal buffer. The buffer in turn includes aborate salt. When dissolved in the water, the treatment compositiongenerally buffers the pH in a range of from about 6.5 to about 8.8. Incertain embodiments, the water preferably has a pH of from about 6.5 toabout 8.4, more preferably from about 7 to 8, and most preferably fromabout 7.2 to about 7.6.

In one embodiment of the present disclosure, the algaecidal bufferpreferably includes a salt selected from the group consisting of saltsof octaborate, salts of pentaborate, salts of hexaborate and mixturesthereof. Suitable salts may include, for instance, sodium salts,potassium salts, lithium salts, magnesium salts, calcium salts, zincsalts, and mixtures thereof. Particularly preferred are sodium orpotassium salts including disodium octaborate salt odium pentaboratesalt, and sodium hexaborate. In certain embodiments, the treatmentcomposition consists essentially of the chlorine-containing sanitizerand the algaecidal buffer. In still further embodiments, the treatmentcomposition consists of only the chlorine-containing sanitizer and thealgaecidal buffer

In still another aspect, the present disclosure provides a method forreducing the rate of growth of algae in swimming pools. According to themethod a volume of water is provided within a swimming pool. A boratesalt selected from the group consisting of salts of octaborate, salts ofpentaborate, salts of hexaborate and mixtures thereof is dissolved inthe volume of water in an amount sufficient to provide a concentrationof borate salt dissolved in the water of from about 0.01 weight % toabout 0.5 weight %. A sanitizer is selected from the group consisting ofhypochlorite salts, sodium dichloro-s-triazinetrione, andtrichloro-s-triazinetrione is also dissolved in the volume of water inan amount sufficient to provide from about 0.1 ppm to about 10 ppm offree chlorine in the water.

In a further aspect, the present disclosure provides a method for makinga borate microemulsion. According to one embodiment, the method includesmixing one part, by weight, acidic borate with from about 0.6 to about1.4 parts, by weight, alkali borate and from about 1.5 to about 3 parts,by weight, water to form a first mixture. The first mixture is reactedat a temperature of from about 32° F. to about 212° F. to provide afirst reaction product which comprises emulsified sodium pentaborate.More preferably, the first mixture is reacted at a temperature of fromabout 40° F. to about 100° F. The first reaction product is then mixedwith an additional from about 0.5 to about 4 parts, by weight, acidicborate and from about 0.5 to about 2 parts, by weight, water to providea second product which comprises emulsified sodium pentaborate andparticulate boric acid suspended therein.

In certain embodiments according to the present disclosure, the acidicborate preferably includes a borate selected from the group consistingof orthoboric acid, metaboric acid, boric oxide, and mixtures thereof.

In certain embodiments according to the present disclosure, the alkaliborate preferably includes a borate selected from the group consistingof sodium borates, potassium borates, lithium borates, and mixturesthereof. More preferably, the alkali borate includes a borate selectedfrom the group consisting of tincal, kernite, anhydrous sodiumtetraborate, sodium tetraborate pentahydrate, sodium tetraboratedecahydrate, and mixtures thereof. Alternatively, the alkali borate mayinclude borate selected from the group consisting of ulexite,colemanite, and mixtures thereof.

In certain embodiments, the first reaction product preferably includesfrom about 25 to about 75 weight percent emulsified sodium pentaborate.The second product preferably includes from about 18 to about 38 weightpercent emulsified sodium pentaborate and from about 18 to about 38weight percent particulate boric acid. More preferably, the secondproduct includes from about 24 to about 32 weight percent emulsifiedsodium pentaborate and from about 24 to about 32 weight percentparticulate boric acid.

In some embodiments, the second product preferably includes from about 8to about 13 weight percent elemental boron. In one embodiment, thesecond product more preferably includes about 11.5 weight percentelemental boron. In another embodiment, the second product morepreferably includes about 10 weight percent elemental boron.

In certain embodiments, the viscosity of the second product ispreferably from about 1000 to about 2000 centipoise at a temperature offrom about 64° F. to about 72° F. More preferably, the viscosity of thesecond product is from about 1200 to about 1520 centipoise at atemperature of from about 66° F. to about 70° F. In certain otherembodiments, the viscosity of the second product is preferably fromabout 1000 to about 3000 centipoise at a temperature of from about 70°F. to about 75° F. More preferably, the viscosity of the second productis from about 2000 to about 2800 centipoise at a temperature of fromabout 70° F. to about 75° F.

In certain embodiments according to the present disclosure, the secondproduct preferably has a density of from about 9 to about 11 pounds pergallon at about room temperature. More preferably, the second producthas a density of from about 9.5 to about 10.5 pounds per gallon at aboutroom temperature.

The pH of the second product preferably ranges from about 6 to about 7.5in certain embodiments. More preferably, the pH of the second productpreferably ranges from about 6.5 to about 7.

In still another aspect, the present disclosure provides a method formaking a borate microemulsion, including at least the steps of: mixingone part, by weight, boric acid with from about 0.6 to about 1.4 parts,by weight, sodium tetraborate and from about 1.5 to about 3 parts, byweight, water to form a first mixture; reacting the first mixture at atemperature of from about 40° F. to about 100° F. to provide a firstreaction product which comprises emulsified sodium pentaborate; andmixing the first reaction product with an additional from about 0.5 toabout 4 parts, by weight, boric acid and from about 0.5 to about 2parts, by weight, water to provide a second product which comprisesemulsified sodium pentaborate and particulate boric acid suspendedtherein.

In certain embodiments, the sodium tetraborate preferably includessodium tetraborate pentahydrate. Also, in certain embodiments, the boricacid preferably includes orthoboric acid.

In some embodiments, the density of the second product is morepreferably about 10.2 pounds per gallon at about room temperature. Inaddition, in some embodiments, the pH of the second product is morepreferably from about 6.7 to about 6.9.

In certain embodiments, the additional boric acid mixed with the firstreaction product preferably includes powdered boric acid.

In some embodiments, the first mixture is preferably reacted in a highshear mixer or a ribbon blender. In addition, the additional boric acidis preferably mixed with the first reaction product using an inlinemill.

The present disclosure also provides a borate microemulsion product. Inone embodiment, the borate microemulsion includes from about 24 to about32 weight percent emulsified sodium pentaborate; and from about 24 toabout 32 weight percent particulate boric acid suspended therein. Themicroemulsion has a density of about 9.5 to about 10.5 pounds per gallonat about room temperature. In certain embodiments, the microemulsion hasa viscosity of about 1200 to about 1520 at a temperature of from about66° F. to about 70° F. In certain other embodiments, microemulsion has aviscosity of about 1000 to about 3000 at a temperature of from about 70°F. to about 75° F.

In certain embodiments according to the present disclosure, the densityof the microemulsion is more preferably about 10.2 pounds per gallon atabout room temperature.

In some embodiments, the pH of the microemulsion is preferably fromabout 6.5 to about 7. More preferably, the pH of the microemulsion ispreferably from about 6.7 to about 6.9.

The borate microemulsion may be diluted with water. In certainembodiments, the microemulsion has a pH of from about 7.0 to about 8.0after dilution in water at a rate of about 1 gallon microemulsion per1000 gallons water. More preferably, the microemulsion has a pH of fromabout 7.2 to about 7.9 after dilution in water at a rate of about 1gallon microemulsion per 1000 gallons water.

In certain embodiments, the borate microemulsion also preferablyincludes an anti-settling agent selected from the group consisting ofxanthan gum, polyacrylates, acrylic acid, agar, carboxymethyl cellulose,clay, and mixtures thereof.

In still another aspect, the present disclosure provides a method forbuffering the pH of a swimming pool. In one embodiment, the methodincludes preparing a borate microemulsion concentrate which includesfrom about 24 to about 32 weight percent emulsified sodium pentaborate;and from about 24 to about 32 weight percent particulate boric acidsuspended therein. The borate microemulsion concentrate is then added tothe water of a swimming pool in a ratio of from about 0.1 to about 1gallons of concentrate per 1000 gallons of swimming pool water. Theborate microemulsion concentrate has an initial pH of from about 6 toabout 7.5 and after mixing with the swimming pool water provides a finalpool water pH of from about 7.2 to about 7.9.

In certain preferred embodiments, the swimming pool includes a poolskimmer device and the borate microemulsion concentrate is mixed withthe swimming pool water using the pool skimmer device. Advantageously,this addition of the borate microemulsion concentrate does not clog thepool skimmer device.

The present disclosure also provides a method for making a boratemicroemulsion with only a single reaction step. In one embodiment, themethod includes the step of mixing one part, by weight, of an alkaliborate is mixed with from about 1 to about 15 parts, by weight, of anacidic borate and from about 1 to about 20 parts, by weight, water toform a mixture; and the step of reacting the mixture at a temperature offrom about 32° F. to about 212° F. to provide a reaction product whichcomprises emulsified sodium pentaborate and particulate boric acidsuspended therein. Preferably, the reaction is carried out in a mixingvessel with a recirculation loop in order to improve the mixingefficiency.

In a more preferred embodiment, one part, by weight, of an alkali borateis mixed with from about 2 to about 5 parts, by weight, of an acidicborate and from about 2 to about 10 parts, by weight, water to form amixture.

In certain embodiments according to the present disclosure, the acidicborate preferably includes a borate selected from the group consistingof orthoboric acid, metaboric acid, boric oxide, and mixtures thereof.

In certain embodiments according to the present disclosure, the alkaliborate preferably includes a borate selected from the group consistingof sodium borates, potassium borates, lithium borates, and mixturesthereof. More preferably, the alkali borate includes a borate selectedfrom the group consisting of tincal, kernite, anhydrous sodiumtetraborate, sodium tetraborate pentahydrate, sodium tetraboratedecahydrate, and mixtures thereof. Alternatively, the alkali borate mayinclude borate selected from the group consisting of ulexite,colemanite, and mixtures thereof.

In certain embodiments, the reaction product preferably includes fromabout 18 to about 38 weight percent emulsified sodium pentaborate andfrom about 18 to about 38 weight percent particulate boric acid. Morepreferably, the reaction product includes from about 24 to about 32weight percent emulsified sodium pentaborate and from about 24 to about32 weight percent particulate boric acid.

In some embodiments, the reaction product preferably includes from about8 to about 13 weight percent elemental boron. In one embodiment, thereaction product more preferably includes about 11.5 weight percentelemental boron. In another embodiment, the reaction product morepreferably includes about 10 weight percent elemental boron.

In yet another aspect, the present disclosure provides a method formaking a borate microemulsion, which includes the steps of: mixing onepart, by weight, alkali borate with from about 1 to about 20 parts, byweight, of a non-borate acid and from about 1 to about 20 parts, byweight, water to form a mixture; and reacting the mixture at atemperature of from about 32° F. to about 212° F. to provide a reactionproduct which comprises from about 18 to about 38 weight percentemulsified sodium pentaborate and from about 18 to about 38 weightpercent particulate boric acid suspended therein.

In certain embodiments, the alkali borate preferably includes a borateselected from the group consisting of tincal, kernite, anhydrous sodiumtetraborate, sodium tetraborate pentahydrate, sodium tetraboratedecahydrate, and mixtures thereof. More preferably, the alkali borateincludes sodium tetraborate pentahydrate.

In certain embodiments, the non-borate acid preferably includes an acidselected from the group consisting of sulfuric acid, sulphur dioxide,sodium bisulphate, potassium bisulphate hydrochloric acid, chlorine,hypochlorous acid, carbon dioxide, carbonic acid, phosphoric acid, andmixtures thereof.

In other embodiments, the non-borate acid preferably includes an organicacid selected from the group consisting of carboxylic acids,dicarboxylic acids, sulfonic acids, and mixtures thereof.

In still another aspect, the present disclosure provides a method formaking a borate microemulsion, which includes the steps of: mixing onepart, by weight, acidic borate with from about 0.05 to about 2 parts, byweight, of a non-borate base and from about 1 to about 3 parts, byweight, water to form a mixture; and reacting the mixture at atemperature of from about 32° F. to about 212° F. to provide a reactionproduct which comprises from about 18 to about 38 weight percentemulsified sodium pentaborate and from about 18 to about 38 weightpercent particulate boric acid suspended therein.

In certain embodiments, the acidic borate includes a borate selectedfrom the group consisting of orthoboric acid, metaboric acid, boricoxide, and mixtures thereof. More preferably, the acidic borate includesorthoboric acid.

In certain embodiments, the non-borate base includes a base selectedfrom the group consisting of sodium hydroxide, potassium hydroxide,calcium hydroxide, magnesium hydroxide, lithium hydroxide, sodium oxide,potassium oxide, calcium oxide, magnesium oxide, lithium oxide, sodiumcarbonate, potassium carbonate, calcium carbonate, magnesium carbonate,lithium carbonate, and mixtures thereof. More preferably, the non-boratebase includes sodium hydroxide. In other embodiments, the non-boratebase may include an organic base such as a primary amine, a secondaryamine, or a tertiary amine.

DETAILED DESCRIPTION

In a first aspect, the present disclosure provides a method for reducingthe rate of growth of algae in a volume of water such as a swimmingpool. According to the method, an effective amount of a treatmentcomposition which includes a chlorine-containing sanitizer and a buffer,generally an algaecidal buffer is dissolved into the volume of water totreat the water, to reduce the growth of algae in the water and tomaintain a given pH range. As used in this context, the term“algaecidal” refers to and includes both compositions which are capableof killing algae and compositions which are capable of suppressing thefurther growth of algae.

The treatment may be used with any type of man made swimming pool orother body of water having a volume of water which is retained within aman made vessel. As used herein, “swimming pools” includes in-groundswimming pools, above-ground swimming pools, indoor swimming pools, anddiving and wading pools, as well as hot tubs. The pool water may beretained by, for instance, cement or concrete walls, metal walls, tiledwalls, plastic walls (such as polyethylene or glass reinforced polymer(GRP)), or a swimming pool liner formed of polymeric film such as vinyl.The treatment method may be used with all sizes of pools which are largeenough to allow a human being to swim or bath therein.

The treatment may also be used to treat fire storage and sprinklertanks, closed loop cooling systems, and open loop cooling systems suchas those used in industrial cooling towers. In addition, the treatmentmay also be effective in other man made bodies of water such as waterfeatures, water fountains, water slides, and theme park water rides suchas “log flumes.” For convenience, however, the use of the treatment isdescribed herein with respect to a swimming pool.

The algaecidal buffer utilized in the treatment composition and methodof the disclosure is selected from the group of salts of octaborate,salts of pentaborate, salts of hexaborate and mixtures thereof. Suitablesalts may include, for instance, sodium salts, potassium salts, lithiumsalts, magnesium salts, calcium salts, zinc salts, and mixtures thereof.Particularly preferred algaecidal buffer salts include potassium andsodium salts, such as disodium octaborate salt (Na₂B₈O₁₃) and sodiumpentaborate salt (NaB₅O₈) as well as sodium hexaborate (Na₂B₆O₁₁). Thisincludes both anhydrous forms of the salts as well as their hydrates, aswell as different salts with different cations such as disodiumoctaborate tetrahydrate (Na₂B₈O₁₃×4H₂O), potassium pentaboratetetrahydrate (KB₅O₈×4H₂O), sodium hexaborate tetrahydrate(Na₂B₆O₁₀×4H₂O) and sodium hexaborate decahydrate (Na₂B₆O₁₀×10H₂O).

Surprisingly, it has been found that the aforementioned octaborate,pentaborate, and hexaborate salts provide superior performance asalgaecidal buffers as compared to other boron-containing compounds suchas sodium tetraborate, i.e., borax (Na₂B₄O₇), and boric acid (H₃BO₃).

The pentaborate, octaborate, and/or hexaborate salts are added to thepool water in an amount which is effective to substantially suppress oreliminate algal growth within the pool water. In certain embodiments ofthe present disclosure, it has been found that dissolution of from about0.01 to about 0.5 weight % of algaecidal buffer in pool water issufficient for this purpose. More preferably, the amount of algaecidalbuffer dissolved in the volume of pool water is preferably from about0.025 to about 0.1 weight % in pool water. Thus, in a 10,000 gallon poolfor example, from about 10 to about 500 pounds of the algaecidal bufferis generally added to the pool water. More preferably from about 25 toabout 100 pounds of the algaecidal buffer is added to the pool water.However, in certain other embodiments of the present disclosure, theamount of algaecidal buffer dissolved in the volume of water ispreferably from about 0.001 weight % to about 0.1 weight %, ofalgaecidal buffer in pool water, and more preferably from about 0.02weight % to about 0.05 weight %.

The algaecidal buffer is preferably added directly to the pool as a drybulk powder or granules. The powder or granules may in some instances beproduced by spray drying or by granulation to form a dry flowablematerial. Formation of the powder by spray drying advantageously leadsto an amorphous non-crystalline structure. This has been found toimprove the immediate dispersion of the powder when added to water aswell as the overall dissolution rate of the powder in the water.

However, the algaecidal buffer may alternatively be added as a liquidconcentrate if desired or as a slowly dissolving solid block. In oneembodiment, for instance, the algaecidal buffer may be provided as amicellar emulsion including from about 30 to about 60 weight percentborates, more preferably from about 45 to about 55 weight percentborates, dispersed in an aqueous suspension. In certain embodiments, theemulsion includes approximately 10 weight percent elemental boron. Thealgaecidal buffer may preferably be added to various locations about thepool to promote treatment of the entirety of the volume. Alternatively,the algaecidal buffer may be added in a single location within the pool.The buffer may also be added directly to a pool skimmer associated witha pool filtration system so as to use the pool pump and filter system toaid in dissolving and distributing the buffer within the pool. This iscontrast to borates such as sodium tetraborate which cannot be added tothe skimmer due to problems with clumping and reaction to form a solidmass that can block the skimmer system.

The pentaborate, octaborate, and/or hexaborate salts used in the presentdisclosure have been found to exhibit very good aqueous solubility andthus the algaecidal buffer powder or granules rapidly disperse anddissolve in the pool water. In general, the algaecidal buffer of thepresent disclosure is substantially dissolved in the volume of poolwater in from about 0.1 to about 50 minutes, and more preferably fromabout 1 to about 5 minutes. When added to the pool water, the algaecidalbuffer salts tend to disperse before reaching the bottom of the pool. Inmost instances, the algaecidal buffer salts of the present disclosurehave been observed to completely dissolve prior to reaching the poolbottom. This is in decided contrast to the use of sodium tetraborateand/or boric acid which have lower aqueous solubilities and tend to formsolid clumps in the pool water and/or encrustations on the innersurfaces of the swimming pool, or unsightly surface floating deposits.

Several benefits and advantages are provided due to the improveddissolution of the algaecidal buffer salts of the present disclosure.Caking and/or clumping of the buffer salts is substantially eliminated.This in turn means that clogging or blockages of swimming pumps andskimmers is also greatly reduced.

In addition, it has also been observed that scale formation on bothmetal and non-metal surfaces within the swimming pool is significantlyreduced. In some instances, corrosion of metal surfaces may also bereduced.

In the past, the addition of chlorine additives to pool water, as wellof use of the water by swimmers, has been found to lead to a decrease ofpool water pH into an acidic range and to the formation of hypochlorousacid, which acts as an eye and skin irritant. Use of the buffers of thepresent disclosure has also been found to reduce the formation ofhypochlorous acid in the pool water and to limit the associated drop inpH. Consequently, eye and skin irritation from the water issubstantially reduced.

In some embodiments of the present disclosure, treatment of the poolwater with salts of pentaborate, octaborate and/or hexaborate may besufficient to substantially suppress or eliminate algal growth withoutuse of any further treatment chemicals. In other embodiments of thedisclosure, however, it may be desirable to combine treatment of thepool water using the aforementioned salts with a further treatment stepof dissolving an effective amount of an additional sanitizer into thevolume of pool water.

For example, effective algaecidal treatment results may be achieved byincluding as an additional treatment agent a sanitizer such aschlorine-containing sanitizers, bromine-containing sanitizers,silver-containing sanitizers, zinc-containing sanitizers, coppercontaining sanitizers, quaternary ammonium-containing sanitizers, ozonesanitizers, UV sanitizers and mixtures thereof. Particularchlorine-containing sanitizers include chlorine gas (which may forexample be prepared by electrolysis of sodium chloride), sodiumhypochlorite, calcium hypochlorite; lithium hypochlorite, sodiumdichloro-s-triazinetrione (dichlor), and trichloro-s-triazinetrione(trichlor). It is particularly preferred to use either dichlor,trichlor, or a hypochlorite salt as an additional treatment agent.

When used in conjunction with salts of pentaborate and/or octaborate,according to the present disclosure, the amount of additional sanitizerdissolved in the volume of pool water is generally sufficient to providefrom about 0.1 to about 10 ppm of free chlorine (Cl^(−ve)) in the poolwater. For calcium hypochlorite, for example, the amount dissolved inthe volume of pool water is preferably sufficient to provide from about0.1 to about 0.5 ppm free chlorine in the pool water. The free chlorinelevel is not necessarily maintained at this level continuously, but itis preferred that the free chlorine level be maintained at this level atroutine intervals in order to remove organic contamination in the waterby oxidization as well as to kill pathogenic organisms.

In certain embodiments of the present disclosure, the treatmentcomposition consists essentially of the chlorine-containing sanitizerand the algaecidal buffer. That is, the treatment composition does notany other additives which would have a substantial effect on the pH ofthe water being treated. In still further embodiments, the treatmentcomposition consists of only the chlorine-containing sanitizer and thealgaecidal buffer

The swimming pool treatment according to the present disclosure has beenfound to remain effective in suppressing algae growth for extendedperiods of time without additional treatment. Moreover, the swimmingpool treatment according to the present disclosure has been found toextend the effective lifespan of chlorine-containing sanitizers whenadded to pool water and thereby reduce the frequency at which suchsanitizers must be replenished in the pool water.

Conventionally, chlorine-containing sanitizers tend to be rapidlyremoved from pool water due to photochemical degradation. If thechlorine-containing sanitizers are not promptly replaced, the pool willthen be susceptible to the rapid and devastating growth of algal bloomsin a short period of time. For example, conventionally usedchlorine-containing sanitizers may be depleted and large algal bloomsmay develop, while a home owner is away on a relatively short summervacation. If this occurs, very large acute doses of shock chlorine willthen be needed to kill and remove the algae by oxidation, and the poolwill be unsuitable for use until the algae is removed and the level offree chlorine in the pool returns to a safe level.

When chlorine-containing sanitizers are used in conjunction with thepresent disclosure, however, the rate of photodegradation of thechlorine has been found to be greatly reduced. The buffer salts of theinvention also directly inhibit the growth of algae and bacteria. Theintervals at which the sanitizers must be replenished are thus greatlyextended. For example, an application once per week or even once permonth can be satisfactory in a pool that previously had requiredapplications once every few days.

Conventionally, pool water, after a chlorine-containing sanitizer isdissolved therein, may remain substantially free of algae for at leastabout 7 days. When an algaecidal buffer is combined with achlorine-containing sanitizer, as according to one embodiment of thepresent disclosure, it has been found that pool water so treated mayremain substantially free of algae for up to about 3 months. When thetwo are combined and the chlorine-containing sanitizer is replenished ona periodic basis, pool water so treated has been found to remainsubstantially free of algae for over 3 years and may continue to remainsubstantially fee of algae indefinitely.

As a further benefit of the swimming pool treatment of the presentdisclosure, it has been observed that dissolution of a pentaborate,octaborate and/or hexaborate salt algaecidal buffer in the pool water,in combination with a sanitizer, acts as a pH buffer for the swimmingpool water.

Specifically, when an effective amount of from about 0.001 weight % toabout 0.1 weight % (and more preferably from about 0.02 weight % toabout 0.005 weight %) of the algaecidal buffer is dissolved in the poolwater, the pH of the pool water is buffered in a range of from about 6.5to about 8.8. More preferably, the water has a pH of from about 7 to 8,and most preferably from about 7.2 to about 7.6. The buffering of thepool water pH in this near-neutral range reduces skin and eye irritationto swimmers which may occur from contact with pool water at other, moreextreme pH ranges. Buffering in this pH range also reduces scaling andmetal corrosion within the pool. Thus this pH range is believed to begenerally ideal for the operation and maintenance of the pool.

As a further advantage, buffering at this pH range is believed to aid inthe retention of dissolved chlorine and to improve the disinfectantproperties of any supplemental chlorine-based sanitizer due to thebalance between free available chlorine and hypochlorous acid whichoccurs at this pH range.

In certain embodiments, the pH buffering action is believed to derivesubstantially entirely from the borate salt and the sanitizer withoutthe need for additional pH adjustment chemicals such boric or otheracids (such as hydrochloric acid) or alkaline bases.

The properties and advantage of the present disclosure are illustratedin further detail in the following nonlimiting examples. Unlessotherwise indicated, temperatures are expressed in degrees Celsius,concentrations of the algaecidal buffer are expressed in weight %, andconcentration of free chlorine are expressed in parts per million (ppm).

Example 1 Borate Biostat Buffer Dissolution Tests

In this example, different forms of borates were added to columns ofwater and a swimming pool to determine their comparative dispersion andrate of dissolution characteristics. The borate forms compared includeddisodium octaborate tetrahydrate, boric acid, sodium tetraborate(borax), and a mixture of boric acid and borax.

Methodology

Two hundred and fifty (250) ml of deionized water was placed in each of4 measuring cylinders to give a 300 mm vertical column of water in eachcylinder to mimic in small scale the depth of water in a swimming pool.To each column was added 0.2 g (0.08 weight %) of either boric acid(obtained commercially as OPTIBOR from U.S. Borax, Inc. of Valencia,Calif.), borax pentahydrate (obtained commercially as NEOBOR from U.S.Borax, Inc. of Valencia, Calif.), disodium octaborate tetrahydrate(obtained commercially as POLYBOR from U.S. Borax, Inc. of Valencia,Calif.) or a mixture made of 0.1 g boric acid with 0.1 g borax. Theresults of the addition were then observed visually and recorded.

Following this initial experiment in the lab, the same test was repeatedat the shallow end of a 10,000 gallon domestic swimming pool with anaddition of 5 lb of each product or of the mixture.

Results

The boric acid was observed to mostly float on top of the water and didnot completely dissolve after addition. The boric acid was also observedto leave an unsightly white dust on the surface of the water. The boraxsank immediately to the bottom of the cylinder and formed an encrustedmass that did not dissolve within a few minutes after addition. Themixture of the boric acid and borax segregated upon contact with thewater with approximately half sinking to the bottom and half floating.In contrast, the disodium octaborate tetrahydrate was observed toimmediately disperse and fully dissolve in a matter of seconds andbefore reaching the bottom of the column. The results obtained in theswimming pool tests were substantially the same as in the initiallaboratory test.

Discussion and Conclusion

From the above results, it was found that when adding a borate to aswimming pool, the use of disodium octaborate tetrahydrate is farpreferred to the use of boric acid, or borax, or mixtures of both boricacid and borax in terms of the rate of product dissolution and the rateat which the pool returns to its original aesthetics. It was observedfrom these tests that the dispersion of material throughout the pool ismore rapid and more uniform with disodium octaborate than with either ofboric acid or borax or mixtures of boric acid and borax.

Example 2 Effect of Disodium Octaborate Tetrahydrate as a ChlorineStabilizer Using Lithium Hypochlorite

In this example, borates, in the form or disodium octaboratetetrahydrate, were added to an aqueous solution of lithium hypochloritein order to determine the effectiveness of disodium octaborate instabilizing a hypochlorite pool sanitizer.

Methodology

Two glass laboratory beakers each with a capacity of 2 liters werepartially filled with chlorinated deionized water (1 liter each) with orwithout added disodium octaborate tetrahydrate. The chlorine solutionswere prepared by first dissolving 0.1 gram of lithium hypochlorite(obtained commercially as SPA TIME lithium hypochlorite) in 1 liter ofdeionized water. 500 ml of this resulting solution was then furtherdiluted to 1 liter with an additional 500 ml deionized water.

The resulting solutions were measured using free chlorine indicatorstrips and found to contain 10 ppm of free chlorine. 0.5 grams ofdisodium octaborate tetrahydrate (obtained commercially as POLYBOR fromUS Borax) was then added to one of the beakers to obtain a 0.05 weight %disodium octaborate tetrahydrate concentration. The second beaker ofchlorine solution was used as a control with no disodium octaboratetetrahydrate added. Both beakers were then immediately placed outside inbright sunlight in August at midday in Rockford, Tenn. The free chlorinecontent in each beaker was then measured using free chlorine indicatorstrips at time intervals of 0 hours, 1.5 hours, and 2.5 hours.

Results

The measured free chlorine concentrations for reach beaker and timeperiod are tabulated below.

Disodium Octaborate Time Control Beaker Tetrahydrate Beaker   0 hr. 10ppm   10 ppm 1.5 hr. 0 ppm 1.0 ppm 2.5 hr. 0 ppm 0.5 ppm

Discussion and Conclusions

These results demonstrate that the addition of disodium octaboratetetrahydrate to chlorinated water reduced the rate of photo-induced lossof free chlorine from the water. This results in an increase in thelongevity of the chorine sanitizer performance and a reduction of theamount of chlorine addition required over a period of time.

While the measured free chlorine disappeared relatively quickly evenfrom the disodium octaborate tetrahydrate treated water, thephoto-degradation of the free chlorine was highly acerbated under thetesting conditions used, i.e., due to the very small volume of waterused in the test and the very strong sunlight on the day of the test. Ina larger body of water, such as a swimming pool, and under less extremeheat and light conditions, the rate of chlorine loss in both thedisodium octaborate-treated water and in the untreated water wouldlikely be slower than the rates observed in this example. However, therate of chlorine loss in the disodium octaborate-treated water wouldstill be slower than in the untreated water under the same heat andlight conditions. Thus, the addition of disodium octaborate was observedto provide a significant benefit in reducing chlorine loss and wouldprovide a benefit in commercial pool treatments by prolonging theantiseptic performance of the chlorine in the pool water and reducingthe amount of chlorine replenishment that needed to be added over aperiod of time.

Example 3 Comparison of Sodium Pentaborate and Sodium Tetraborate asChlorine Stabilizers Using Dichlor

In this example, two different borates, sodium pentaborate and sodiumtetraborate (borax), were added to aqueous solutions of sodiumdichloro-s-triazinetrione dihydrate (“dichlor”) pool sanitizer in orderto compare the relative effectiveness of the two borates in stabilizingthe dichlor sanitizer.

Methodology

Two glass laboratory beakers each with a capacity of 1 liter werepartially filled with chlorinated deionized water (0.5 liters each) withor without added pentaborate (sodium pentaborate) or borax (borax). Thechlorine solutions were prepared by first dissolving 0.05 g of dichlor(in the form of a vinyl pool shock product available under the tradenameAQUACHEM from Bio-Lab, Inc. of Lawrenceville, Ga.) in 2 liters ofdeionized water. 500 ml of this resulting solution was then added to thebeakers.

The resulting solutions were measured using free chlorine indicatorstrips and found to contain 10 ppm free chlorine. 0.25 grams of sodiumpentaborate (obtained commercially as SOLUBOR DF from US Borax) was thenadded to one of the beakers to obtain a 0.05 weight % sodium pentaborateconcentration. 0.25 g of borax (obtained commercially as NEOBOR from USBorax) was added to the other beaker to obtain a 0.05 weight % boraxconcentration. Both beakers were then immediately placed outside inbright sunlight at the beginning of October 2006 at 3:50 pm in Rockford,Tenn. The free chlorine content in each beaker was then measured at 0time, 15 minutes, 30 minutes, 45 minutes 60 minutes, 80 minutes and 980minutes.

Results

The measured free chlorine concentrations for each beaker and timeperiod are tabulated below.

Time Sodium Pentaborate Beaker Borax Beaker 0 10 ppm 10 ppm 15 minutes10 ppm 7.5 ppm 30 minutes 7.5 ppm 3 ppm 45 minutes 5 ppm 1 ppm 60minutes 5 ppm 0.5 ppm 80 minutes 3 ppm 0 ppm 980 minutes (next morning)1 ppm 0 ppm

Discussion and Conclusions

These results demonstrate that the treatment of water by addition ofsodium pentaborate to chlorinated water reduces the rate ofphoto-induced loss of free chlorine from the water as compared totreatment of water by the addition of sodium tetraborate (borax). Thus,treatment according to the disclosure was observed to increase thelongevity of chorine sanitizer performance and reduce the amount ofchlorine addition required over a period of time.

While the measured free chlorine was observed to disappear relativelyquickly even from the sodium pentaborate treated water, thephoto-degradation of the free chlorine was observed to be highlyacerbated under the testing conditions used characterized by the use ofa small volume of water and strong sunlight on the day of the test. In alarger body of water, such as a swimming pool, and under less extremeheat and light conditions, the rate of chlorine loss in both the sodiumpentaborate-treated water and in the borax-treated water is expected tobe slower than the rates observed in this example. However, based on theobserved results, the rate of chlorine loss in the sodiumpentaborate-treated water would be expected to be slower than in theborax-treated water under the same heat and light conditions. Thus, theaddition of sodium pentaborate according to the disclosure would providea significant benefit in commercial pool treatments by prolonging theantiseptic performance of the chlorine in the pool water and reducingthe amount of chlorine replenishment that needed to be added over aperiod of time.

Example 4 Comparative Example Using Lake Water

In order to compare the effectiveness of disodium octaboratetetrahydrate to sodium tetraborate (borax) in suppressing algae growthin previously untreated water, approximately 5 liters of clear lakewater was collected from the Little River tributary of Lake Loudoun onthe Tennessee River. From this lake sample, three 1 liter glass beakerswere each filled with 900 mL of lake water. Disodium octaboratetetrahydrate was added to one beaker to provide a concentration of 0.1weight percent disodium octaborate tetrahydrate. Sodium tetraborate wasadded to a second beaker to provide a concentration of 0.1 weightpercent sodium tetraborate. The third beaker was left as an untreatedcontrol. The three samples, which were collected in August, were thenleft outside, fully exposed to the sun, for a period of two months.

After the two month period, the samples were then visually inspected foralgal growth. The samples were also analyzed using a Spectronic Genesys20 spectrophotometer from Thermo Scientific. This analysis was conductedby testing for absorbance at 330 nm.

In the visual inspection excessive algal growth was observed in theuntreated sample, slight growth was observed in the borax treated sampleand very minimal growth was observed in the DOT treated sample.

These findings were corroborated by the absorbance readings obtainedspectrophotimetrically and given below:

Sample Absorbance (Abs.) Untreated (Control) 0.258 Sodium tetraborate0.01 Disodium octaborate tetrahydrate 0.004

The higher absorbance readings in the control and the borax samples areindicative of higher algal growth in the water samples.

Example 5 Corrosiveness Comparative Example

In this example, the corrosiveness of disodium octaborate tetrahydratewas compared to that of boric acid. The test was conducted with two 500mL beakers which were each filled with 200 mL of water (199.75 g). 0.5grams of disodium octaborate tetrahydrate was added to the first beakerand 0.5 grams of boric acid was added to the second beaker, thusproviding a 0.25 weight % solution in each beaker.

A steel framing nail was then placed in each solution and left for aperiod of two weeks. After the two week period, the nail in the boricacid solution was observed to be significantly corroded, and thesolution was observed to have turned brown due to the presence of thecorrosion product (likely iron oxide) in solution. On the other had, thenail in the disodium octaborate tetrahydrate solution was observed to befree of significant corrosion, and the solution was observed to be clearand free of corrosion by-products.

Example 6 Use of Sodium Hexaborate as a Buffer

In this example, different borates were added to swimming pools,together with a chlorine-based sanitizer, in order to measure pH andfree chlorine (Cl⁻) levels in the swimming pools over a period it time.

Three substantially identical, 2000 gallon above-ground swimming poolswere used for the tests. Each pool was initially filled withapproximately 2000 gallons of tap water, and then 500 milliliters oflake water was added to each pool to inoculate the pool water withalgae. The testing was conducted during the month of September at alocation near Knoxville, Tenn.

In the first pool, approximately 4 pounds of sodium tetraborate wasadded to the pool water. Approximately 4 pounds of sodium hexaborate wasadded to water of the second pool. The third pool was used as a controlwith no form of borate being added to the pool water. The borates in thefirst and second pools were then allowed to mix overnight.

The following morning, initial pH and chlorine measures were taken foreach pool at approximately 9:45 am. Approximately 0.3 pounds of calciumhypochlorate was then added to the water in each of the three swimmingpools at approximately 10 am. The pH and chlorine levels in each of thepools were then measured periodically over the course of the day. Themeasurements obtained were as follows:

Free chlorine level (ppm) for swimming pool water with: Time No borateSodium tetraborate Sodium hexaborate 9:45 am 0 0 0 10:00 am 0 0 0 10:55am 10 10 10 11:15 am 10 10 10 12:00 pm 10 10 10 12:40 pm 10 10 10 1:25pm 5 10 9 2:10 pm 3 5 6.5 2:50 pm 1 0.5 1.5 3:30 pm 0.5 0 0.75 4:10 pm 00 0.75 5:00 pm 0 0 0

pH for swimming pool water with: Time No borate Sodium tetraborateSodium hexaborate 9:45 am 7.0 >8.4 7.2-7.8 10:00 am 7.6 >8.4 7.2-7.810:55 am 8.4 >8.4 7.2-7.8 11:15 am 8.4 >8.4 7.8-8.4 12:00 pm 8.4 >8.47.8-8.4 12:40 pm 7.8 >8.4 7.8-8.4 1:25 pm 6.8 >8.4 7.2-7.8 2:10 pm6.8 >8.4 7.2-7.8 2:50 pm 6.8 >8.4 7.2-7.8 3:30 pm 6.8 >8.4 7.2-7.8 4:10pm 6.8 >8.4 7.2-7.8 5:00 pm 6.8 >8.4 7.2-7.8

These results show that the sodium tetraborate slowed the decompositionof the free chlorine to some degree as compared to the control with noborates added. However, the sodium hexaborate was more effective thanthe sodium tetraborate and provided the greatest reduction in thedecomposition rate for the free chlorine.

In addition, the results also show that the sodium hexaborate bufferedthe water at a lower pH, generally in the range of from about 7.2 toabout 7.8. In contrast the sodium tetraborate buffered the water at a pHin excess of 8.4, which was the maximum pH value measurable on the pHmeter used during this test. The lower and more neutral pH of the sodiumhexaborate buffered water would generally be more comfortable forswimming and using the pool, improve water clarity, and maximize theperformance of chlorine.

In a further aspect, the present disclosure also provides a borate-basedmicroemulsion concentrate suitable for use in the treatment of swimmingpools and similar structures. In addition to water, the microemulsionproduct includes at least emulsified sodium pentaborate and particulateboric acid suspended therein. In general, the microemulsion product, inits concentrated form, includes from about 18 to about 38 weight percentemulsified sodium pentaborate and from about 18 to about 38 weightpercent particulate boric acid. More preferably, the microemulsionconcentrate includes from about 24 to about 32 weight percent emulsifiedsodium pentaborate and from about 24 to about 32 weight percentparticulate boric acid. Thus, the microemulsion concentrate generallyincludes from about 8 to about 13 weight percent elemental boron. Incertain embodiments, the microemulsion concentrate more preferablyincludes about 10 weight percent elemental boron or about 11.5 weightpercent elemental boron.

In certain embodiments, the microemulsion concentrate may also includefrom about 0.01 to about 0.75 weight percent of an anti-settling agentselected from the group consisting of xanthan gum, polyacrylates,acrylic acid, agar, carboxymethyl cellulose, clay, and mixtures thereof.

The product is referred to as a “microemulsion” in that it includes bothborate materials which are fully dissolved in the aqueous solvent andmicroscopic solid particles (micelles) of borate materials which areemulsified but are not fully dissolved in the water solvent. To thenaked eye, the product has a milky or emulsion-like appearance; however,the solid micelles of undissolved borates are sufficiently small thatthe product feels smooth and free of grit or particles when touched byhand.

The result is a product which is quite viscous and has a cream likeconsistency. In certain embodiments, when tested using a BrookfieldDV-I+Viscometer, the viscosity of the microemulsion product has beenfound to generally be from about 1000 to about 2000 centipoise at atemperature of from about 64° F. to about 72° F. More preferably, theviscosity of the microemulsion product ranges from about 1200 to about1520 centipoise at a temperature of from about 66° F. to about 70° F.However, in certain other embodiments, the microemulsion may be somewhatmore viscous, having a viscosity from about 1000 to about 3000centipoise, and more preferably from about 2000 to about 2800centipoise, at a temperature of from about 70° F. to about 75° F.

The density of the microemulsion concentrate may range from about 9 toabout 11 pounds per gallon at about room temperature, more preferablyfrom about 9.5 to about 10.5 pounds per gallon at about roomtemperature. Still more preferably, the density of the microemulsionproduct is about 10.2 pounds per gallon at about room temperature

The pH of the microemulsion product, in its concentrated form, isgenerally from about 6 to about 7.5 in certain embodiments. Morepreferably, the pH of the microemulsion concentrate is from about 6.5 toabout 7. Most preferably, the pH of the microemulsion concentrate isfrom about 6.7 to about 6.9.

In one embodiment, the borate-based microemulsion concentrate may beprepared by mixing one part, by weight, of an acidic borate with fromabout 0.6 to about 1.4 parts, by weight, of an alkali borate and fromabout 1.5 to about 3 parts, by weight, water to form a first mixture.The first mixture is then reacted to provide a first reaction productwhich comprises emulsified sodium pentaborate. The first reactionproduct is then mixed with an additional from about 0.5 to about 4parts, by weight, acidic borate and from about 0.5 to about 2 parts, byweight, water to provide a second product, the microemulsionconcentrate, which includes both emulsified sodium pentaborate andparticulate boric acid suspended therein.

Preferably, the acidic borate used in preparing the first mixtureincludes at least one borate selected from the group consisting oforthoboric acid, metaboric acid, boric oxide, and mixtures thereof. Morepreferably, the acidic borate includes a boric acid, and mostpreferably, the acidic borate includes orthoboric acid.

The alkali borate used in preparing the first mixture preferablyincludes at least one borate selected from the group consisting ofsodium borates, potassium borates, lithium borates, and mixturesthereof. Sodium borates, such as tincal (Na₂B₄O₇×10 H₂O), kernite(Na₂B₄O₇×4 H₂O), anhydrous sodium tetraborate, sodium tetraboratepentahydrate, sodium tetraborate decahydrate are more preferred.Alternatively, borate minerals such as ulexite (NaCaB₅O₉×8 H₂O) orcolemanite (CaB₃O₄(OH)₃×H₂O) may also be used. Anhydrous sodiumtetraborate, sodium tetraborate pentahydrate, and sodium tetraboratedecahydrate are particularly preferred, with sodium tetraboratepentahydrate being most preferred.

Once mixed, the acidic borate and the alkali borate are reacted with oneanother. In general, this reaction may be carried out at any temperaturefrom about 32° F. to about 212° F. More preferably, this reaction may becarried out at a temperature of from about 40° F. to about 100° F. Thereaction of the acidic borate and the alkali borate is preferably, butnot necessarily, carried out in a high shear mixer or a ribbon blendersuch as a Saracco 3813 or a Marion BPC 4296.

Reaction of the acidic borate and the alkali borate results in theformation of a first reaction product. The first reaction productincludes a substantial amount of sodium pentaborate in an emulsifiedform. Preferably, the first reaction product includes from about 25 toabout 75 weight percent emulsified sodium pentaborate.

The first reaction product is then mixed with additional acidic borate,preferably powdered boric acid, to provide a second product, themicroemulsion concentrate. This mixing step is preferably, but notnecessarily, carried out using an inline mill such as a Greerco 457SPLN.

According to another embodiment of the present disclosure, theborate-based microemulsion concentrate may be prepared in a process withonly a single reaction step. In this process, the entire amounts of theacidic borate, the alkali borate, and the water are combined initiallyand allowed to react. Generally, one part, by weight, of an alkaliborate is mixed with from about 1 to about 15 parts, by weight, of anacidic borate and from about 1 to about 20 parts, by weight, water toform a mixture. In a more preferred embodiment, one part, by weight, ofan alkali borate is mixed with from about 2 to about 5 parts, by weight,of an acidic borate and from about 2 to about 10 parts, by weight, waterto form a mixture. In general, the same acidic borates and alkaliborates may be used in the single reaction step process as in the tworeaction step process. A preferred acid borate is orthoboric acid whilea preferred alkali borate is sodium tetraborate pentahydrate. Xanthangum or a similar anti-settling agent may also be added to the mixture.

This mixture is then allowed to react to provide a microemulsion productincludes emulsified sodium pentaborate and particulate boric acidsuspended therein. According to this single reaction step process, themixing and reaction of the aforementioned components is preferablycarried out in mixing vessel having a recirculation loop, driven by anappropriate recirculation pump, to improve the mixing efficiency of thevessel.

In one example of the single reaction step process, the initial mixtureis about 43 weight percent orthoboric acid, 14 weight percent sodiumtetraborate pentahydrate, about 0.3 weight percent xanthan gum, andabout 42 weight percent water. After reaction, the final product is madeup about 30 weight percent emulsified sodium pentaborate and about 30weight percent suspended particulate boric acid, along with the xanthangum and water.

Alternatively, the borate-based microemulsion concentrate may beprepared in a process with only a single reaction step in which analkali borate is mixed and reacted with non-borate acid. For instance,one part, by weight, alkali borate may be mixed with from about 1 toabout 20 parts, by weight, of a non-borate acid and from about 1 toabout 20 parts, by weight, water to form a mixture. This mixture is thenreacted at a temperature of from about 32° F. to about 212° F. toprovide a reaction product which comprises from about 18 to about 38weight percent emulsified sodium pentaborate and from about 18 to about38 weight percent particulate boric acid suspended therein.

In certain embodiments, the alkali borate preferably includes a borateselected from the group consisting of tincal, kernite, anhydrous sodiumtetraborate, sodium tetraborate pentahydrate, sodium tetraboratedecahydrate, and mixtures thereof. More preferably, the alkali borateincludes sodium tetraborate pentahydrate.

In certain embodiments, the non-borate acid preferably includes an acidselected from the group consisting of sulfuric acid, sulphur dioxide,sodium bisulphate, potassium bisulphate hydrochloric acid, chlorine,hypochlorous acid, carbon dioxide, carbonic acid, phosphoric acid, andmixtures thereof. In this context, materials such as sulphur dioxide,bisulfate salts, chlorine, and carbon dioxide are considered to be acidssince they yield acids when dissolved in water.

In other embodiments, the non-borate acid preferably includes an organicacid selected from the group consisting of carboxylic acids,dicarboxylic acids, sulfonic acids, and mixtures thereof. Suitablecarboxylic acids include, for example, formic acid, acetic acid, andpropionic acid. Suitable dicarboxylic acids include, for example, oxalicacid and succinic acid.

In still another alternative, the borate-based microemulsion concentratemay be prepared in a process with only a single reaction step in whichan acidic borate is mixed and reacted with non-borate base. For example,one part, by weight, acid borate may be mixed with from about 0.05 toabout 2 parts, by weight, of a non-borate base and from about 1 to about3 parts, by weight, water to form a mixture. This mixture is thenreacted at a temperature of from about 32° F. to about 212° F. toprovide a reaction product which comprises from about 18 to about 38weight percent emulsified sodium pentaborate and from about 18 to about38 weight percent particulate boric acid suspended therein.

In certain embodiments, the acidic borate includes a borate selectedfrom the group consisting of orthoboric acid, metaboric acid, boricoxide, and mixtures thereof. More preferably, the acidic borate includesorthoboric acid.

In certain embodiments, the non-borate base includes a base selectedfrom the group consisting of sodium hydroxide, potassium hydroxide,calcium hydroxide, magnesium hydroxide, lithium hydroxide, sodium oxide,potassium oxide, calcium oxide, magnesium oxide, lithium oxide, sodiumcarbonate, potassium carbonate, calcium carbonate, magnesium carbonate,lithium carbonate, and mixtures thereof. More preferably, the non-boratebase includes sodium hydroxide.

In other embodiments, the non-borate base may include an organic basesuch as a primary amine, a secondary amine, or a tertiary amine

Once prepared, the microemulsion concentrate may be stored for longperiods in a stable form without significant precipitation orsolidification of the borates. It has been observed that even after ayear of storage, the microemulsion concentrate is still usable andgenerally requires only mild shaking or agitation prior to being used totreat various water bodies such as fountains, pool sand spas.

When added to swimming pools, fountains, spas and the like, the boratemicroemulsion product has been found to aid in the prevention of algaegrowth and in the killing of pathogens, particularly when used incombination with a chlorine-based sanitizer. In addition the boratemicroemulsion product has been found to reduce scaling and corrosion, toreduce skin and eye irritation of bathers, to compensate for lowercyanuric acid or free chlorine concentrations in the water, to reducenecessary pump filtration times, to help water clarity and to reduce orprevent mosquito larvae development in same water bodies if abandonedand left without chlorine (e.g. after a natural disaster or after homeforeclosures). Further, the microemulsion concentrate is particularlywell suited for use in the treatment of swimming pools in order tobuffer the pH of the pool water.

The microemulsion concentrate may be added to the swimming pool water ata ratio of from about 1000 to about 5000 gallons of water per 1 gallonof microemulsion concentrate. More preferably, the concentrate isdiluted in the swimming pool water at water at a rate of about 1 gallonmicroemulsion per 3000 gallons water. Alternatively, the concentrate isdiluted in the swimming pool water at water at a rate of about 1 gallonmicroemulsion per 2000 gallons water.

Addition of the microemulsion concentrate to swimming pool water inthese proportions leads to an elemental boron concentration in the waterof from about 10 to about 100 parts per million (ppm), more preferablyfrom about 30 to about 80 ppm.

In certain instances, the microemulsion concentrate may be added to theswimming pool at the pool skimmer and the recirculation of the skimmermay be used to mix the concentrate with the pool water. Advantageously,it has been found that the microemulsion concentrate readily blends withthe pool water in this manner and does not clog the pool skimmer or itsassociated piping.

As noted above, the pH of the microemulsion product, in its concentratedform, is generally from about 6 to about 7.5, preferably, from about 6.5to about 7, and most preferably, from about 6.7 to about 6.9. Thus theconcentrate is generally slightly acidic in nature.

Surprisingly, however, addition of the concentrate has been found tolead to a slightly alkaline condition in the pool water. After additionof the concentrate, the pool water has been found to typically bebuffered in a pH range of from about from about 7.0 to about 8.0 after.More preferably, the pH is buffered in a range from about 7.2 to about7.9.

The foregoing description of preferred embodiments for this inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Obvious modifications or variations are possible inlight of the above teachings. The embodiments are chosen and describedin an effort to provide the best illustrations of the principles of theinvention and its practical application, and to thereby enable one ofordinary skill in the art to utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claimswhen interpreted in accordance with the breadth to which they arefairly, legally, and equitably entitled.

1-17. (canceled)
 18. A borate microemulsion comprising: from about 24 toabout 32 weight percent emulsified sodium pentaborate; and from about 24to about 32 weight percent particulate boric acid suspended therein,wherein the microemulsion has a viscosity of about 1000 to about 3000 ata temperature of from about 70° F. to about 75° F. and a density ofabout 9.5 to about 10.5 pounds per gallon at about room temperature. 19.The borate microemulsion of claim 18, wherein the microemulsion has a pHof from about 6.5 to about
 7. 20. The borate microemulsion of claim 18,wherein the microemulsion has a pH of from about 7.0 to about 8.0 afterdilution in water at a rate of about 1 gallon microemulsion per 1000gallons water.
 21. The borate microemulsion of claim 18, wherein themicroemulsion has a pH of from about 7.2 to about 7.9 after dilution inwater at a rate of about 1 gallon microemulsion per 1000 gallons water.22. The borate microemulsion of claim 18, wherein the microemulsioncomprises about 10 weight percent elemental boron.
 23. The boratemicroemulsion of claim 18, wherein the microemulsion comprises ananti-settling agent selected from the group consisting of xanthan gum,polyacrylates, acrylic acid, agar, carboxymethyl cellulose, clay, andmixtures thereof.
 24. A method for buffering the pH of a swimming pool,the method comprising: preparing a borate microemulsion concentratecomprising from about 24 to about 32 weight percent emulsified sodiumpentaborate and from about 24 to about 32 weight percent particulateboric acid suspended therein; and mixing the borate microemulsionconcentrate with the water of a swimming pool in a ratio of from about0.1 to about 1 gallons of concentrate per 1000 gallons of swimming poolwater, wherein the borate microemulsion concentrate has an initial pH offrom about 6 to about 7.5 and after mixing with the swimming pool waterprovides a final pool water pH of from about 7.2 to about 7.9.
 25. Themethod for buffering the pH of a swimming pool of claim 25, wherein theswimming pool includes a pool skimmer device and the boratemicroemulsion concentrate is mixed with the swimming pool water usingthe pool skimmer device without clogging the pool skimmer device. 26-33.(canceled)
 34. A method for making a borate microemulsion, the methodcomprising the steps of: mixing one part, by weight, alkali borate withfrom about 1 to about 20 parts, by weight, of a non-borate acid and fromabout 1 to about 20 parts, by weight, water to form a mixture; andreacting the mixture at a temperature of from about 32° F. to about 212°F. to provide a reaction product which comprises from about 18 to about38 weight percent emulsified sodium pentaborate and from about 18 toabout 38 weight percent particulate boric acid suspended therein. 35.The method of claim 34, wherein the alkali borate comprises a borateselected from the group consisting of tincal, kernite, anhydrous sodiumtetraborate, sodium tetraborate pentahydrate, sodium tetraboratedecahydrate, and mixtures thereof.
 36. The method of claim 34, whereinthe alkali borate comprises sodium tetraborate pentahydrate.
 37. Themethod of claim 34, wherein the non-borate acid comprises an acidselected from the group consisting of sulfuric acid, sulphur dioxide,sodium bisulphate, potassium bisulphate hydrochloric acid, chlorine,hypochlorous acid, carbon dioxide, carbonic acid, phosphoric acid, andmixtures thereof.
 38. The method of claim 34, wherein the non-borateacid comprises an organic acid selected from the group consisting ofcarboxylic acids, dicarboxylic acids, sulfonic acids, and mixturesthereof.
 39. A method for making a borate microemulsion, the methodcomprising the steps of: mixing one part, by weight, acidic borate withfrom about 0.05 to about 2 parts, by weight, of a non-borate base andfrom about 1 to about 3 parts, by weight, water to form a mixture; andreacting the mixture at a temperature of from about 32° F. to about 212°F. to provide a reaction product which comprises from about 18 to about38 weight percent emulsified sodium pentaborate and from about 18 toabout 38 weight percent particulate boric acid suspended therein. 40.The method of claim 39, wherein the acidic borate comprises a borateselected from the group consisting of orthoboric acid, metaboric acid,boric oxide, and mixtures thereof.
 41. The method of claim 39, whereinthe acidic borate comprises s orthoboric acid.
 42. The method of claim39, wherein the non-borate base comprises a base selected from the groupconsisting of sodium hydroxide, potassium hydroxide, calcium hydroxide,magnesium hydroxide, lithium hydroxide, sodium oxide, potassium oxide,calcium oxide, magnesium oxide, lithium oxide, sodium carbonate,potassium carbonate, calcium carbonate, magnesium carbonate, lithiumcarbonate, and mixtures thereof.
 43. The method of claim 39, wherein thenon-borate base comprises sodium hydroxide.